An active shutter 3D technology for performing a 3D display can be achieved by 3D shutter glasses cooperative with a high refresh rate LCD (Liquid Crystal Display), wherein the 3D shutter glasses are substantially two pieces of liquid crystal screens which are controllably switched on/off, respectively. A liquid crystal layer of each liquid crystal screen has both black and white states. When powered on, the glasses switch to the black state. When powered off, they switch to the white, namely, transparent state. Thus, either piece of the liquid crystal screens may receive a left-eye frame signal from the LCD, and the other piece of the liquid crystal screens may receive a right-eye frame signal from the LCD. Meanwhile, the LCD emits synchronous signals via a signal transmission device to accomplish synchronization of the liquid crystal screens switching of the 3D shutter glasses with the left-eye and the right-eye frames switching of the LCD.
The liquid crystal molecules have a characteristic that if an electric field direction applied on two sides of the liquid crystal layer is kept for a long time, the characteristic of the liquid crystal molecules will be damaged and will no longer be rotated depending on the changes of the electric field, thereby expressing different grayscales. Thus, for each specific interval, the direction of the electric field must be changed to inverse the liquid crystal molecules, in order to avoid the destruction of the characteristic of the liquid crystal molecules. Due to this reason, the industry has developed a variety of driving methods to achieve the inverse of liquid crystal molecules (polarity inversion), such as dot-inversion, frame inversion, column inversion, and row inversion.
Commonly, data signals transmitted via data lines are divided by employing a common voltage (Vcom) as a reference voltage into a positive polarity (+) data signal which has a higher voltage than the common voltage, and a negative polarity (−) data signal which has a lower voltage than the common voltage. The positive polarity data signal denotes that its voltage is higher than the common voltage while the negative data signal denotes that its voltage is lower than the common voltage. In theory, when the same grayscale value is expressed by the positive and the negative polarity data signals, respectively, the display effects are consistent.
When the active shutter 3D LCD adopts the dot inversion driving method to drive the image pixel, the pixel polarity of the LCD is as shown in FIG. 1, where the frames 01 to 04 are four consecutive frames. In a common LCD, since the odd frames are configured to display the left-eye image (or right-eye image), the even frames are configured to display the right-eye image (or left-eye image). That is, if the image signal of the LCD treated as a left-eye image signal is a high grayscale signal (such as white signal) and treated as a right-eye image signal is a low grayscale signal (such as black signal), then it will appear that a positive polarity pixel (as a pixel displaying a positive polarity data signal) at the upper-left side of the frame 01 shown in FIG. 1 is configured to display the high grayscale signal, a negative polarity pixel (as a pixel displaying a negative polarity data signal) at the upper-left side of the frame 02 is configured to display the low grayscale signal, and a positive polarity pixel at the upper-left side of the frame 03 is again configured to display the high grayscale signal. while the low grayscale signal appears, either positive or negative polarity data signals will be close to the common voltage, and while in the high grayscale signal, either positive or negative polarity data signals will be far from the common voltage. This results in the LCD pixel being kept actually in either a positive polarity (displays a positive polarity data signal) or a negative polarity (displays a negative data signal), readily making an image sticking phenomenon occurring in the LCD.
When the active shutter 3D LCD adopts the two dot inversion driving method to drive the image pixel, the pixel polarity of the LCD is as shown in FIG. 2, where the frames 01 to 04 are four consecutive frames. If the image signal of the LCD appears with a left-eye image signal which is a high grayscale signal, and a right-eye image signal which is a low grayscale signal, then the positive polarity pixel at the upper-left side of the frame 01 shown in FIG. 2 will be configured to display the high grayscale signal, and the positive polarity pixel at the upper left-side of the frame 02 will be configured to display the low grayscale signal, while the negative polarity pixel at the upper-left side of the frame 03 will be configured to display the high grayscale signal, and the negative polarity pixel at the upper-left side of the frame 04 will be configured to display the low grayscale signal.
Therefore, since each pixel of the LCD displays either positive polarity high grayscale signals or negative polarity high grayscale signals, the occurrence of image sticking can be prevented.
But during the display process of the LCD, the frames 02 and 04 in the FIG. 2 are usually right-eye images, and the frames 01 and 03 are usually left-eye images. Since the frames 01 and 02 have the same polarity data signals, it is necessary to reallocate the charges of the pixels when the LCD displays the data signals. Thus, the pixel brightness will be greater after the reallocation and the screen brightness of the frame 02 will be greater than that of the frame 01. Similarly, the screen brightness of the frame 04 will be greater than that of the frame 03. That is, the brightness of the right-eye image is greater than that of the left-eye image. This will easily generate 3D ghosting, and affect the display quality of the LCD.
Therefore, it is necessary to provide an LCD panel and an LCD device to solve the existing problems.